There are many uses for floatable structures that include extendible elements such as antennas and the like. Such structures have been used in the past for transmitting a radio signal or the like to indicate the location of the floatable structure or some other related object such as some type of submerged object such as a submarine. Other floatable structures have been utilized to transmit signals to indicate the location of personnel who may be floating in the water in view of the fact that they had to ditch an aircraft. In a similar manner other such floatable structures have been utilized to indicate the location of personnel from a ship that has been sunk.
For instance, U.S. Pat. No. 2,907,875 discloses an emergency radio transmitter for use in broadcasting or indicating the location of forced landings of aircraft on the sea which has a conical shaped tower having a radio antenna which is mounted on a base, and the tower and the base are capable of being inflated by gas from a pressure cartridge or container so that the device can be inflated to make it floatable. Unfortunately, there are several disadvantages related to such a device. For instance, in view of the fact that the antenna is contained within a mast or conical shaped tower, the length of the antenna is of necessity limited. In a similar manner in view of the construction of the mast and the base and the absence of a weight or similar structure, this type of device can be easily tipped over and hence is generally not usable in rough water. Another U.S. Pat. No. 3,068,471 discloses a floating antenna that is adapted for use with receivers or transmitters located aboard small vessels, lifeboats, rafts or the like. This antenna includes an elongated, expandable, watertight casing that contains an antenna wire. A source of compressed gas is also provided that is utilized to fill the casing with compressed gas so that it extends outward lengthwise. The inflated antenna structure then lies on its side in the water so that the antenna wire is generally parallel to the surface of the water. This device has one advantage over the previous device in that practically any length of antenna wire can be utilized whereas that is not the case in the other device. However, with this device the antenna wire is not located in an upright position and for many types of uses this might degrade the ability of the antenna wire to appropriately receive or transmit signals.
Another U.S. Pat. No. 3,312,902 discloses a self-erecting floating structure which does have provision for an upright antenna wire or cord which is located in the interior of an inflatable balloon. However, in view of the fact that the balloon is essentially spherical in shape, there is an inherent practical limitation on the length of the cord or wire that could be utilized. Moreover, in view of the substantially spherical shape of the balloon, it is doubtful whether this structure will maintain its proper upright relationship when floating in rough water. Another U.S. Pat. No. 4,053,896 discloses a self-erecting buoy antenna which may be released from a submerged submarine and the like to float to the surface to provide an erected antenna. In view of the construction of this buoy, the length of its antenna is inherently limited. In addition, it should be noted that this self-erecting buoy structure has no provision for an inflatable buoyant member and hence is not readily storable in a compact configuration. Another U.S. Pat. No. 4,110,724 discloses an extendible antenna apparatus which is released from a submarine or the like. This antenna apparatus has provisions for extending an antenna of substantial length above the level of the water. However, this antenna can be maintained in position only for a comparatively short period of time since its upper portion is only held up by a parachute. As a consequence, transmission or receiving time from such an antenna is of necessity limited.
In view of the foregoing it is apparent that there is a need for a compact, self-erecting floatable structure that has provisions for extending a long antenna or the like and maintaining that long antenna or similar structure in its upright or operational mode even though the floatable structure is located in rough water. The current invention provides such a self-erecting floatable structure that maintains an elongated element in a curled or collapsed configuration and also maintains a buoyant member in a compact configuration prior to activation. Upon activation the elongated element is automatically extended, and the inflatable member is inflated; and in view of the configuration of the inflatable member and the addition of a suitably located weight, the elongated member can be of substantial length and yet be maintained in its upright position in rough water. Moreover, in view of the construction of the self-erecting floatable structure, it is capable of being packaged into an extremely compact structure.